Photographic developers



United States Patent Ofiice 2,981,623 Patented Apr. 25, 1961 2,981,623 PHOTOGRAPHIC DEVELOPERS .Lothar Burgardt, Leverkusen-Bayerwerk, Willibald Pelz,

Koln-Stammheim, Ottmar Wahl, Opladen, and Heinz Sassmann, Burscheid, Germany, assignors to Agfa Aktiengesellschaft, Leverlrusen, Germany, a corporation of Germany No Drawing. Filed Mar. 14, 1955, Ser. No. 494,221

Claims priority, application Germany Mar. 15, 1954 11 Claims. (Cl. 96-66) The present invention relates to photographic developer substances and more especially to substances derived from 4-amino-pyrazolones-(S -As photographic developers, it has been the practice hitherto generally to employ substances which belong to the class of aromatic polyvalent hyd'roxy compounds, amino-hydroxy compounds or polyvalent amino compounds. Compounds of the heterocyclic class are known to have developer properties (German Patent No. 646,516), inter alia, S-pyrazolones, substituted in the 4-position with an amino group, which S-pyrazolorles contain the m-aminoketone structurein the heterocyclic nucleus. These aminopyrazolones are, however, exclusively substances which are alkylated in the 3-position. These compounds have not been used in practice as developers, since they are quite unstable with relatively small intensity of development and show a strong tendency to fogging.

It has now been found that 4-aminopyrazolones of the following constitution do not have these properties which are disadvantageous for use in practice as developers:

wherein R may represent -OH, O-alkyl, O-aryl, O-aralkyl NH or substituted NH groups, NHNH or substituted hydrazide groups, NHOH or an azide group and also alkyl, aryl or aralkyl radicals. R may represent hydrogen, alkyl, aralkyl, aryl groups or substituted aryl groups or heterocyclic radicals.

It has surprisingly been found that such compounds represent excellent photographic developer substances, since they operate without fogging with a surprisingly high development intensity and are sufficiently stable in order to be used practically as developers. The developer substances may either be used independently or with advantage in combination with known developer substances, whereby they either work more quickly owing to their great rapidity, i.e. develop images to the same gamma value in a shorter time, or they develop a specific photographic material to higher gamma values with the same development period. Moreover, the property of the present invention may be incorporated into silver super-additivity may also frequently be used with adhalide emulsion layers which are developed by alkaline solution containing, if desired, developer substances.

Examples of the aforementioned pyrazolones are:

4-amino-5-pyrazolones-3-carboxylic acid ethyl ester, 1-pheny1-4-amino-5-pyrazolones-3-carboxylic acid ethyl ester, 1-phenyl-4-amino-5-pyrazolone-3-carboxylic acid amide, l (p ethoxy phenyl) 4 amino- 5 pyrazolone-3-carboxylic acid ethyl ester, 1-phenyl-3-(methane sulphohydrazo-carbonyl)-4-amino-5-pyrazolone or l-(psulphophenyl) 4 amino 5 pyrazolone 3 carboxylic acid methyl ester. A large number of further compounds are possible, according to substitution of the radicals R and R The production of these aminopyrazolones is carried out according to known processes. For example, suitable pyrazolones may be transformed by treatment with nitrite into the isonitroso-compounds and the latter by reduction with tin into the associated amino compounds. The reduction of the isonitroso-cornpounds may also be carried out according to other known processes, for example with zinc and glacial acetic acid or catalytically. Another available method for the production of such compounds is based upon the reductive splitting of azo dyestuifs, which are obtained. by coupling suitable pyrazolones with diazonium salts.

EXAMPLE 1 For developing a commercially available black-andwhite film with the sensitivity of 17/10 DIN, there is employedthe following developer solution:

Sodium sulphite anhydrous g Hydroquinone g 3 Borax g 3 KBr g 0.5 1-phenyl-4-amino-S-pyrazolone 3 carboxylic acid amide hydrochloride g 2.5 Water cc 1000 The developer solution has a soft action and is finegrained with high speed. With a development period of nine minutes, the film shows a fogging of 0.08. The

Development period (minutes) Gamma value Fogging V 3 1-phenyl-4-amino-pyrazolone-3-carboxylic acid amide is prepared as follows:

Yield: 235 g. of isonitroso derivative.

50 g. of the isonitroso product are dissolved in 500 cc. of glacial acetic acid and treated at 40-50" C. With zinc dust until decolorization. After filtering the solution and passing in hydrogen chloride, the hydrochloride of the aminopyrazolone is obtained in good yield; it is filtered with suction, the filtered substance dissolved in little water While hot, precipitated with hydrochloric acid and dried in vacuum over caustic potash after filtering with suction.

Yield: 40 g.

EXAMPLE 2 For developing a commercially available black-and- White film With the sensitivity of 17/10 DIN, there is employed the following developer solution:

Anhydrous sodium sulphite g 80 Borax g 3 KBr g 0.5 Metol g 1.5 Methane-sulphohydrazide of 1-phenyl-4-arnino-5- pyrazolone-S-carboxylic acid hydrochloride g 9.5 Water cc 1000 Strongly-acting fine-grain developer. (Development Development period (minutes) Gamma value Fogging The methane sulfohydrazide of 1-phenyl-4-amino-5 pyrazolone-3-carboxylic acid is prepared as follows:

206 g. of 1-phenyl-pyrazolone-3-carboxylic acid ethylester are introduced into 120 cc. of alcohol and heated to boiling temperature for hours with 120 cc. of hydrazinehydrate (83%) while stirring under reflux. After cooling the reaction mixture is introduced with stirring into 200 cc. of hydrochloric acid (20%) and 200 g. of ice, filtered with suction, the filtered substance washed with water and dried.

Yield: 220 g. of hydrazide; M.P.: 252-254 C.

220 g. of the hydrazide are dissolved in 430 cc. of sodium hydroxide solution (5%) and reacted dropwise at 1015 C. with g. of methane sulfochloride with the simultaneous addition of sodium hydroxide solution (10%) at such a rate that the solution is kept alkaline against phenolphthalein. The solution is stirred for a further 30 minutes and precipitation effected With hydrochloric acid (10%) after filtering, then filtered with suction and the filtered substance washed. The wet filter cake is dissolved in sodium hydroxide solution (10%), rnixed with 70 g. of nitrite and introduced with stirring into 300 cc. of hydrochloric acid and 700 g. of ice. The isonitroso product obtained is filtered with suction, the filtered substance stirred with water, filtered with suction and dried.

Yield: 250 g.

The isonitroso compound can be reduced with tin sponge and hydrochloric acid according to the process described in Arch. Pharm., 278 (1940), p. 330.

EXAMPLE 3 Anhydrous sodium sulphite g 125 Soda g 12 KBr g 1.5 4-amino-5-pyrazolone-3-carboxylic acid ethyl ester hydrochloride g 13 Water cc 1000 The developer develops negatives brilliantly with finegrain and free from fogging. (Development period: eight minutes.)

'4-amino-5-pyrazolone-3-carboxylic acid ethyl ester is prepared as follows:

Yield: 430 g.

430 g. of the pyrazolone are dissolved in 1000 cc. of hydrochloric acid 1:1) at 50 C., the undissolved portion is separated by filtering and the solution is mixed at lO-15 C. with 170 g. of nitrite in 300 cc. of water. After filtering with suction, washing water and drying 380 g. of isonitroso derivative are obtained. The deriva tive is mixed with 100 cc. of alcohol, reacted while stirring with 1000 cc. of hydrochloric acid and reduced by gradual addition of 250 g. of tin sponge within 5 hours. The hydrochloride is filtered with suction, dissolved in 1000 Iclc. of hot water, filtered and precipitated in the cold wit cc. of hydrochloric acid. After filtering with suction, washing with little water and drying in vacuum.

340 g. of the developer substance are obtained.

EXAMPLE 4 Anhydrous sodium sulphite g 40 Potash g 40 KBr g 2 Hydroquinone g 6 1 phenyl 4 amino 5 pyrazolone 3 carboxylic acid amide hydrochloride g 10 Water cc 1000 Very powerful negative developer. (Development period: three minutes.) I

KBr

ment period: forty seconds.)

1-phenyl-4-amino-5-pyrazolone-3-carboxylic acid hydrazide can be prepared as follows:

l-phenyl-5-pyrazolone-3-carboxylic acid ethyl ester is converted to the isonitroso compound according to Arch. Pharm., 278 (1940), p. 330.

130 g. of the isonitroso compound are stirred at room temperature for 6 hours with 130 g. of hydrazine hydrate (78%), reacted with methanol and filtered with suction.

The reaction product is reduced with tin sponge and hydrochloric acid according to Arch. Pharm, 278 (1940), p. 330.

EXAMPLE 6 Metol g 1 Sodium sulphite anhydro g 13 Soda g 26 KBr g-.. l

1 phenyl 4 amino 5 pyrazolone 3 carboxylic acid ethyl ester hydrochloride g 8 Water cc 1000 Normal developer for silver bromide and silver chloride papers.

This aminopyrazolone is produced according to Arch. Pharm, 278 (1940), p. 330.

EXAMPLE 7 In the developer of Example 3, the hydrochloride of 4-amino-5-pyrazolone-3-carboxylic acid ester is replaced by 15 g. of 1-(p-sulfophenyl)-4-amino-5-pyrazolone-3- carboxylic acid ethyl ester. The developer is of high stability and develops negatives brilliantly and free from fogging.

1 (p' sulfophenyl) 4 amino 5 pyrazolone 3 carboxylic acid ethyl ester is prepared as follows:

31.2 g. of 1-(p'-sulfophenyl)-5-pyrazolone-3-carboxylic acid ethyl ester are dissolved in 150 cc. of sodium hydroxide solution mixed with 7.0 g. of nitrite dissolved in little water, and introduced dropwise with stirring at 5l0 C. into hydrochloric acid. The isonitroso product precipitating in yellow flocs is filtered With suction, the filtered substance stirred with hot alcohol and dried by suction filtering.

34 g'. of the nitroso compound are mixed with stirring with 20 cc. ofalcohol and 120 cc. of hydrochloric acid and reduced with 24 g. of tin sponge as usual. The aminopyrazolone is filtered with suction and recrystallized from water.

6 High-speed fine-grain developer; development period: 8 minutes.

1-phenyl-4-amino-S-pyrazolone-3-carboxylic acid-(ethanolamide) is prepared as follows:

20.6 g. of l-phenyl-5-pyrazolone-3-carboxylic acid ethyl ester and 20 cc. of ethanol amine (50%) are heated under reflux to C. for 5 hours, diluted with water and introduced with stirring into hydrochloric acid (10% The reaction product is filtered with suction and the filtered substance recrystallized from methanol (50% Yield: 28 g. (Wet).

The ethanol amide is dissolved in sodium hydroxide solution (3%), mixed with 8 g. of nitrite, introduced with stirring into hydrochloric acid (10%), filtered with suction and recrystallized from alcohol.

Yield: 23.5 g.

23.5 g. of the isonitroso product are dissolved in cc. of methanol, mixed with 1 g. of Raney nickel and stirred at 6070 C. in the autoclave until hydrogen absorption is complete. The hydrogenation solution is filtered with suction in the heat and precipitated with hydrochloric acid.

Yield: 18 g.

EXAMPLE 9 1 (p-aminophenyl)-4-amino-5-pyrazolone-3-carboxylic acid ethyl ester hydrochloride g 3 Sodium sulfite anhydrous g 40 Hydroquinone g 6 Soda g 20 Potassium bromide -g 1 Water cc Up to 1000 Soft-acting negative developer for orthochromatic and panchromatic photographic materials; development period: 5 minutes.

l-(p'-aminophenyl) 4 amino-5-pyrazolone-3-carboxylic acid ethyl ester is prepared as follows:

27.7 g. l (p'-nitrophenyl)-5-pyrazolone-3-carboxylic acid ethyl ester are dissolved in 150 cc. of sodium hydroxide solution (3%.), reacted with 7.5 g. of nitrite and introduced with stirring into 100 cc. of hydrochloric acid and 100 g. of ice. The isonitroso product formed is filtered In the developer of Example 4, the hydrochloride of 1-phenyl-4-amino-5-pyrazolone-3-carboxylic acid ester is replaced by 10 g. of l-(p' ethoxyphenyl)-4-amino-5-pyrazolone-3-carboxylic acid. A negative developer is thus obtained.

Development periods: 3-4 minutes.

1-(p'-ethoxy-phenyl) 4 amino-5-pyrazolone-3-carboxylic acid is prepared as follows:

20 g. p-ethoxyphenylhydrazine-hydrochloride are introduced into 100 cc. of alcohol,

10 g. of sodium acetate are added and reacted at room temperature dropwise with 20 g. of oxalate. After stirring for one hour the mixture is'filtered with suction and the filtered substance recrystallized from alcohol. 1-(p'-ethoxyphenyl)-5-pyrazolone-3-carboxylic acid is obtained by stirring the ester in 2 N sodium hydroxide solution for some hours and isolated by acidifying the alkaline solution.

16 g. of the carboxylic acid are dissolved in 70 cc. of sodium hydroxide solution (4%), mixed with 4.5 g. of nitrite and introduced with stirring into 100 cc. of hydrochloric acid (1:1). The isonitroso product formed is filtered with suction, the filtered substance Washed with Water and dried. The reduction is effected with tin spouse and hydrochloric acid in the usual manner.

EXAMPLE l1 1 (2'-tetrahydrothiophenesulfone)-4-amino-5-pyrazolone-3-carboxylic acid ethyl ester hydrochloride g 14 Sodium sulfite anhydrous g 125 Soda 6 Potassium bromide g 2.5 Water cc Up to 1000 Very soft fine-grain developer; development period: 12-14 minutes.

1 (2 tetrahydrothiophenesulfone) 4 amino 5 pyrazolone-3-carboxylic acid ethyl ester is prepared as follows:

31.5 g. of an aqueous hydrazine solution (35%) are reacted with 16.0 g. of butadiene sulfone, kept at 75 C. for 30 hours and the major quantity of water removed in vacuum.

15 g. of the resulting hydrazine are heated to 45 C. for

5 hours with 21 g. of sodium oxalate,

50 cc. of alcohol (50%) and 6.6 cc. of glacial acetic acid. The alcohol is distilled off in vacuum, the residue suspended with dilute hydrochloric acid, filtered with suction and the filtered substance recrystallized from acetic acid.

22' g. of the resulting pyrazolone are dissolved in sodium hydroxide solution (5% mixed with 7 g. of nitric and introduced with stirring into hydrochloric acid filtered with suction and the filtered substance dried.

12 g. of the isonitroso compound formed are reduced in the usual manner in 10 cc. of alcohol and 48 cc. of hydrochloric acid with 4.6 g. of tin sponge.

EXAMPLE 12 1 phenyl 4 amino 5 pyrazolone 3 carboxylic acid g 1.6 Sodium sulfite anhydrous g 45 Hydroquinone g 1.2 Soda g 8 Potassium-meta bi-sulfite (K S O g 4 Potassium bromide g 1 Water cc Up to 1000 Normal negative developer; development periods: 10 12 minutes.

1 phenyl 4-amino-5-pyrazolone-3-carboxylic acid is prepared as follows:

1 phenyl 5 pyrazolone-S-carboxylic acid is reacted with benzene diazonium chloride as usual.

30.8 g. of the resulting azo dyestuif are'suspended with 50 cc. of alcohol and 120 cc. of hydrochloric acid and then stirred with 25 g. of tin sponge until decolorization, filtered With suction, the filtered substance boiled with hydrochloric 8 acid (3%) and water, filtered with suction and the filtered substance washed with water.

What we claim is:

1. The process of developing silver halide layers which comprises applying to said'layers a compound having a formula selected from the group consisting of and wherein R is a radical selected from the group consisting of OH, O-alkyl, O-aryl, O-aralkyl, NH NH-- NH and -NHOH, and R is selected from the group consisting of hydrogen, alkyl, aralkyl, aryl and Z-tetrahydrothiophene sulfone radicals, in an alkaline medium.

2. A photographic developing composition consisting essentially of a compound having a formula selected from the group consisting of wherein R is a radical selected from the group consisting of OH, O-alkyl, O-aryl, O-aralkyl, NH NHNH and NH-OH, and R is selected from the group consisting of hydrogen, alkyl, aralkyl, aryl and 2-tetrahydroth-iophene sul-fone radicals, plus a compound selected from the group consisting of pyrocatechol, hydroquinone,

pyrogallol, p-methyl-amino-phenol, N-p-oxyphenylglycin, oand p-phenylendiamines.

3. A photographic developer comprising a silver halide developing compound having a formula selected from the class consisting of:

5. A photographic developer according to claim 3, wherein the first named compound is 1-(p'-ethoxyphen yl) -4-amino-5-pyrazolone-3-carboxylic acid.

6. A photographic developer according to claim 3, wherein the first named compound is 4-amino-5-pyrazolone-3-carboxylic acid ethyl ester.

7. A photographic developer according to claim 3, wherein the first named compound is l-phenyl-4-amino- 5-pyrazolone-3-carboxylic acid hydrazide.

8. A photographic developer according to claim 3, wherein the first named compound is 1-(p'-aminophenyl)- 4-amino-5-pyrazo1one-3-carboxylic acid ethyl ester.

9. A photographic developer according to claim 3 wherein said silver halide developing agent is l-phenyl- 4-amino-5-pyrazolone-3-carboxylic acid.

10. In a silver halide developer mixture having a silver halide developer combined with an alkali metal sulfite, the improvement according to which the developer is a compound whose formula is selected from the group consisting of and References Cited in the file of this: patent UNITED STATES PATENTS 1,937,844 Reed Dec. 5, 1933 2,139,870 Wilmanns et a1. Dec. 13, 1938 2,637,732 Schmid et a1. ,May 5, 1953 2,731,473 Taub Jan. 17, 1956 OTHER REFERENCES Siewert: Chem. Abstracts, vol. 35, C01. 32 32 (1941). Friedman: History of Color Photography, 1944, page 365. 

1. THE PROCESS OF DEVELOPING SILVER HALIDE LAYERS WHICH COMPRISES APPLYING TO SAID LAYERS A COMPOUND HAVING A FORMULA SELECTED FROM THE GROUP CONSISTING OF 